Bank of New Zealand failure caused by Melbourne power outage at National Australia Bank

BNZ customers couldn't use ATMs, Eftpos, internet banking, or physical bank branches for several hours yesterday. Photo / File

A power outage across the Tasman has been revealed as the source of a major Bank of New Zealand failure.

BNZ customers found they couldn't use ATMs, Eftpos, internet banking, or physical bank branches for several hours yesterday.

Communications manager Cliff Joiner said it was caused by an outage at one of the Melbourne systems areas for the National Australia Bank - BNZ's parent company.

He said the outage caused a series of failures on both sides of the Tasman.

Joiner said each system had to be rebooted individually, which is why some customers continued to have problems after the initial resolution.

The National Australia Bank is promising to compensate customers who suffered financial losses because of the outage.

However, Joiner says BNZ hasn't made a decision on compensation yet.

He said the outage had not compromised the personal information of customers.